Semiconductor devices, such as lasers and photodetectors, generally are formed from a semiconductor wafer substrate. In the manufacture of such devices, the wafer substrate is separated, or cleaved, into bars of semiconductor material. These bars of semiconductor material may be further cleaved to form individual semiconductor devices.
Conventional methods for cleaving a wafer substrate generally include scribing or scoring the wafer substrate and then cleaving the substrate along the scoring line through some form of physical contact of an apparatus with the substrate. For example, U.S. Pat. No. 5,171,717 (Broom et al.) describes a method whereby a semiconductor wafer is scribed and then placed between two flexible transport bands. The transport bands are guided around a curved surface having a large radius. This surface applies a bending moment to the scribe lines, thereby cleaving the wafer.
U.S. Pat. No. 5,719,077 (Chakrabarti et al.) describes an apparatus which holds a semiconductor material between a fixed jaw and a rotatable jaw. The rotatable jaw rotates to cleave the semiconductor material. U.S. Pat. No. 5,154,333 (Bauer et al.) describes a device having a pair of pole shaped jaws of different lengths. One of the jaws has a weight on it to provide a downward force on the semiconductor bar being cleaved. As the semiconductor bar comes into contact with the two jaws, the uneven forces of the jaws causes a shearing force to cleave the semiconductor bar.
A problem incurred with cleaving semiconductor material by physically contacting the material is an uneven cleaved surface. If semiconductor material having an uneven cleaved surface is incorporated within an optical device, such as a laser, it may lead to insufficient light output or complete failure of the device.
As described in U.S. patent application Ser. No. 08/970,982, entitled "METHOD AND APPARATUS FOR CLEAVING SEMICONDUCTOR MATERIAL," the entire disclosure of which is incorporated herewith by reference, a continuous stream of gas may be used to alleviate the above discussed cleaving problems. However, certain problems leading to a less than optimal cleaving efficiency have been encountered under some conditions of operation with the use of a continuous stream of gas. Specifically, it has been determined that under certain conditions a continuous stream of gas creates a high incident pressure. The high pressure tends to cause the film layer carrying the semiconductor material to vibrate. The vibrations can dislodge the semiconductor material from this carrier film layer. Further, it has been noted that venting the continuous gas stream in such a way to minimize turbulence is difficult. The turbulence may alter the air pattern, resulting in the semiconductor material not receiving a substantially perpendicular force from the stream, thereby reducing cleaving efficiency.